Aerial device



Nov. 28, 1939. c. B. CHUPP mam. DEVICE Filed Aug. '1, 1936 4 Sheets-Sheet 1 ATTORNEYJ NOV. 28, 1 c B CHUPP AERIAL DEVICE Filed Aug, 1. 1936 v 4 sham-sheaf: 3

' A'ITORNEXJ Nov. 28, 1939;

c B. CHUPP Imam. mavzca Filed Aug. 1,1936

. 4 Sheet-Shet' 4 INVENTOR '-Patented Nov. 28, 1939 UNITED STATES PATENT OFFICE This invention relates to aerial devices, primarily captive flight devices (although in certain aspects it is capable of use also in machines adapted for free flight), and to methods of flying such devices; and it is concerned especially with devices which may be generaly classed as kites, the invention being particularly directed to kites or similar aerial devices havingrotative sustaining blades. V

One of the primary objects of the invention is to provide an aerial device, particularly of the captive type, which is capable of sustension' by virtue of breezes of extremely low velocity.

Another important object of the invention is to substantially improve the stability of such devices.

Still another object is to'render it possible for the operator to exert a measure of control over the kite, particularly through the intermediation of the kite string.

Still-further, the invention contemplates: the

' provision of a kite in which all or a part of the by means of said rotor and/or its movable mounting; and the interconnection or other coordina:

tion of the pivoted rotor axis with the kite string or its connecting means.

Still further, the invention contemplates the coordination, in a captive aerial device; of an autorotative sustaining and stabilizing rotor and nonrotative stabilizing and/ or sustaining surfaces, in a novel and effective manner; the provision .of means for adjustablylocating the fulcrum of the rotor axis on the kite relative to the center of gravity thereof as well as relative to the non-.

rotative surfaces; the provision of means for adjusting the interconnection between the kite string and the tilting rotor axis; and the provision of means for adjusting the kite to fly at various desired altitudes in breezes of varying strength, preferably by means of one or more of the adjustmentdevices just mentioned, and/or by means providing for substitution of rotor blade elements of different contour and/or size.

Among other features contemplated by the invention are:v improvements in the autorotative sustaining blades themselves and in the frame or rigid structure of the device; and in general the provision of a kite of sturdy construction, attractive appearance, and considerable efliciency, at relatively low cost.

Still further, the invention involves an improved method of flying such kites. v

How the foregoing objects and advantages are obtained, together with such others as may be incident to the invention or may occur to those skilled in the art, will be evident from the following description taken together with the accompanying drawings, in which drawings:

Figure 1 is a front elevational view of the captive aerial device of the present invention in its present preferred embodiment;

' horizontal;

Figure 4 illustrates the device in association with a preferred form of launching and handling mechanism; and

Figure 5 is an illustration of a man-carryingkite constructed in accordance with the present invention, showing its use in associationwith a naval vessel.

Referring first to Figs. 1 to 3, the frame of the device comprises a central longitudinal memher I, a central upright member 5 spaced from the front end of the longitudinal member about one-third (or slightly less) of the length thereof, a main transverse member-.16 located at the extreme forward end of the longitudinal member, one rearward diagonal member I, bracing the member 5 to the member 4, and two forwardly and laterally diverging members 8, 8, bracing the upright member 5 to the transverse member 6. While the frame members may be made of aluminum alloy or other suitable'tubing, and joined in any desired manner, I have shownthem as being'made from. wooden sticks, joined by small aluminum fittings 9, I0, ll, i2, 13, etc.

The device is provided at its forward end with lateral stabilizing means, comprising 'a pair, of

fixed surfaces I4, one at each side of the craft, set at a substantially positive dihedral angle (a suitable angle. having been found to be with respect to the horizontal). These surfaces may be made of thin fiat sheets of balsa wood, or the sufficiently far forward to place their centers For stabilization in pitch, there is provided.

adjacent the rear end of the longitudinal. member 4 a, transverse tail surface l1, also of balsa wood, which is secured beneath the stick 4 as '1 by means of a faired or smoothed wooden block ill; the tail plane I1 being desirably about equal to the area of the two lateral planes l4 combined, and being set at a substantially negative angle of incidence (for example considered with 15 relation to the angle of incidence of the planes l4 when viewed in the direction of the longitudinal axis of the stick 4. Furthermore, the negative tail setting is negative with relation to a plane perpendicular to the axis of the rotor (hereinafter to be described) throughout the range of adjustment of, the latter. Considered in another way, when the tail plane is flying approximately horizontally the surfaces l4 and the angle of attack of the rotor are both positive.

.For directional, andalso to some extent for lateral, stability, I provide a vertical stabilizing fin IQ, of high aspect ratio, whiohis also of balsa wood and may be let into a slit at the rear end of the stick 4; andfor a similar purpose I may supplement the vertical tail fin IS with a fin 20 extending'rearwardly. and downwardly from the upright post or pylon 5, and secured in the member 1 by beinglet through a vertical slit therein.

It seems, by test, to be suitable to make thecombined areas of the two vertical fins approximately equal to the area of the tail plane or to the com bmed areas of the lateral stabilizing surfaces.

The surface I9 is given a'rearward rake and surface 20 a downward inclination, primarily in order to provide ample clearance for the rotor blades now to be described.

The rotor may be made up of vtwo elongated blades or wings 2|, having an overall span'about equal to the overall length'of the craft, the aspect 4 ratio of each blade being about l2 or I3. I have found it satisfactory to make these of balsa wood strips, with an approximately fiat under surface and a slightly cambered upper surface, the lead mg edge portion of the blade, however, as indicated at 22 being preferably formed of a narrow stripof more robust wood, such as spruce,which strengthens the blade and brings the sectional center of gravity 9. little further forward. The

blades may be initially .set at a slight positive angle of incidence, when at rest, as indicated by i the position of thetrailing edge 23 (Figure 3).

They are secured to the hub 24 by means of a pivot 25, which passes through a.- transverse aperz; ture in the hub and through a' pair of ears 28 5 ing, the assembled. root end being preferably bound round with thread or wire, as shown at 21. As clearly seen in Figure 2 the axis of the flapping hinge 25 makes an acute angle (prefa er'ably just a little less than a right angle) with 7 the leading edge of the blade, the direction of rotation being indicated .by an. arrow, 50 that as the blades fiap upwardly they decrease their incidence slightly. The root end of each blade has secured on' its .under face a smallrubber bumper 75 or the. like 23,.so thatwhen the blades drop slightly below the true radial position they are supported against the hub 24. r I

The rotorhub 24 is mounted, as'by small ball bearings (the casings of which are shown at 29,

29) in a non-rotative tubular sleeve 30. The

non-rotative sleeve 30 is strapped or otherwise secured to an extension or stick 3| which is pivoted bya fulcrum 32 (offset rearwardly from the rotor hub axis) and mounted in one of the holes 33 which are formed in the V-shaped aluminum 10 bracket 34 which is secured at 35, 35 to the upright stick 5. The bracket 34 in the embodiment shown, is actually composed of two separate right member 5, the hub 30 also fitting between 15 said J plates, ,with' its pivot 32 extending as a through-bolt through both plates as well as the hub extension stick 3|. Said stick 3| also lies between the two plates of the bracket 34 and extends downwardly therebelow. The location of 0 the rotor axis may be variously adjusted by shifting the fulcrum 32 to various of the holes 33, as will be referred to later on.

At the forward corner of the V-shaped bracket there is a stick 36, the end of-whichfits between 25 the two plates of the bracket and is pivoted therein by means, of a cross stick or dowel 31, from the outer end of which guide wires or bracing cords 38 extend downwardly and forwardly to a point of connection with the lower end of the 30 stick 36, where said bracing cords may; be secured thereto as by a cord or wire winding 39.

Atthe extreme lower or forward end of the stick 36 there is screwed into the stick or otherwise secured thereto a ring member 40, or any other 35 suitable means for attaching the kite string. Also secured at this point is a flexible stay cord 4!, which at its other end is secured, as by a the length of the stay cord 4| (which in Figure 3 45 is shown as still "somewhat slack).

Intermediate its ends but relatively close to it upper end, the stick or rigid tow-member 36 has a pivotal connection 43 to one end of a link member 44, the other end of which is pivoted at 5 45 to the lower portion of the rotor hub extension 3|, adjustment holes 46 being provided, in order to regulate the relative angles between the rotor axis and the stick 36, and to alter the geometry of the linkage. For convenience the link 44 is 55 made of two aluminumfstrips, as shown in Figures 1 and 2, one lying on each side of the members 36 and. 3|, the pins 43 and 45 serving as through-bolts. U

From the foregoing description it will be seen that changes in the angular position of the stick 36 on its fulcrum 31, due to variations in the pull on the kitestring. either by the action of the operator or by virtueof change in wind velocity will always be accompanied (assuming for the ct. moment a fixed attitude of the frame of the device) by a tilting of'the axis of.the rotor hub 24 about its fulcrum 32. Furthermore; because of the diflfere'ncesin the distances between the several fulcrums 32, 31, 43, and 45, in the embodimentshown, the range of rotor tilt is reduced somewhat from the range of the tilt of the kite string connecting arm 36. In other words, the linkage between the pivoted lever 36 and the pivoted rotor hub is designed to. produce a some- 76 what smaller rangev of angular variation of the 3, and assuming that there is a very light breeze blowing in the direction of the arrow Bl, the kite string will extend in the direction of the stick 36, at a very slight inclination to the horizontal,

the stick being substantially in the full 'line position shown. Under these conditions the rotor axis will be tilted upwardly and rearwardly, the axis extension 3| being in the position shown in full line so that the rotor as a whole has a very high angle of attack with respect to the relative air flow Bl. The pull of the kite string will, of course, be substantially in the direction of the axis of the stick 36.indicated by the arrow Pl, (i. e., along a line extending to the rear of .the rotor center, which is the point of intersection of the rotor axis with the blade axes) and the lift of the rotor will lie close to the axis of the hub, in

. the direction of the arrow Ll.

The weight of the machine will be acting through the center of gravity G (which lies substantially below and slightly behind the rotor fulcrum) such weight acting in the direction of the arrow W. For a given wind velocity, the rotor axis willtake such a position about its fulcrum that the lift thrust Ll will lie at a position of equilibrium between the thrusts PI and W.

With a substantial increase in the breeze, as represented for example by the arrow B2, the thrust of the rotor will increase and raise the machine to a higher altitude, until thethrust line L2 assumes a new position ofequilibrium between the direction of pull P2 of the kite string (which is now forwardly of the rotor center) and the weight of the machine acting in the direction W; the rotor hub tilting about its fulcrum 32 to the necessary position of equilibrium. The angle of attack of the rotor indicated by the dot and dash line position of the blades at Ma. will at the same time be reduced by virtueof the linkage connecting the rotor axis with the kite string stick 36. The stiffer the breeze, the greater will be the thrust of the rotor, and the angle of the kite string will steepen as the breeze increases; the kite under some conditions, attaining a position directly over the head of the operator.

It may be here noted that the blades 2| in their full line position and also in their dot and dash line positons Ila are shown at their drooped angle which is the angle of rest, but it will be understood that in actual flight, when the rotor is turning, the individual blades will assume angles inclined upwardly from a true radial position on the hub as they are at all times free to flap on the pivot axis 25 to positions of .equilibrium between the lift and centrifugal forcesacting on the blades, the average upward coning angle being about 6 with respect to a plane perpendicular to the axis of rotation.

Let us assume now that the kite is again flying in a breeze of the velocity Bl. If a sudden wind gust oracceleration occurs, the rotor will speed up and its thrust acting in the direction Ll is'increased in magnitude. This creates a substantial moment arm acting about the kite stick fulcrum 3'l,'turning the body of .the kite will, of. course, rise to a higher altitude, remainduced by virtue of the angularity of the pivot axis 25. The device is further adjustable with respect to 'the light wind and high wind conditions, by shifting the rotor fulcrum point 32 forwardly and rearwardlyto different holes 33, for high wind conditions the fulcrum being moved forwardly and for low wind conditions, rearwardly. The fulcrum may also be adjusted to different heights, to alter the relation of the rotor 'ing in, a position of equilibrium. Similarly, by

to the center of the gravity and with respect to other parts of the craft.

As before mentioned, the fins IQ-Qand 20 are inclined, one rearwardly and the other downwardly. This not only gives ample room for rotation and flapping of the rotor blades but also for tilting of the rotor axis, without having said blades foul on said surfaces. In addition, it will be noted that this arrangement is such that blades of larger diameter may be substituted, if desired; for example, if extremely light winds are encountered; this being accomplished bypulling the root end of the wing out of the forked fitting, and substituting a new one.

I have found, in very light machines, that the I range of wind velocities in which the device will fly, and the range of angles which the rotor may assumeis substantially enlarged by. some automatic variation of incidence of the blades (as is obtained by the angularity of their flapping pivot). Without this feature, the individual blades may cone up excessively and under some circumstances autorotation would cease. The obliquity of the flapping pivots, in conjunction with the tilting ability of the rotor axis, also improves the operation of the kite during launching and landing. I

In considering longitudinal stability and balance,'it should be noted that the arrangement provides that the upward thrust of the rotor normally lies between the downward component of .so arranged that this tendency is counterbalanced by the downward thrust component of the kite string. In consideringdirectional stability, it will be observedthat the pull of the kite string is located forwardly of the center of gravity and the stabilizing effect of the surfaces [9 and 20 a is located rearwardly thereof. In considering the matter of lateral stability it should be noted that the dihedral surfaces It and the laterally rigid stick connection 36 cooperate to attain this end. i In general, as to the location of the various fulcrum points as seen in Figure 3, it seems de- 'sirable that the rotor' blade fulcrum 25 intersect the axis of the rotor hub and be located above the level of the hub-tilting fulcrum 32,'that the tilting fulcrum be located rearwardly of the hub axis and the stick fulcrum 3] be located substantially forwardly thereof and below the rotor center; and that the link 44 be fulcrumed at 43 below the fulcrum 3land fulcrumed at 45 still farther below the fulcrum 32. r

By reference now to Figure ,4, it will be seen that ,I provide a launching and securing device comprising a pole4l (such as a fishing rod) on which is mounted a reel 48, with the string 36' extending through an eye 49 at the end of said pole and coupled to the ring 40 of the stick 36. With the device suspended on the string at the tip end of the pole, it may be carried to the field of operations, the device hanging approximately in the position shown.- As the wind catches the, rotor blades, they will cone up steeply until they are individually at negative incidence, with the wind blowing directly through the rotor from its under side. As they commence to rotate and pick up speed, the blades pivot more nearly to a radial position on the hub arid come gradually into a more normal range ofincidence and the rotor axis to a more normal inclination, whereupon the string is paid'outlat less speed than the breeze) and the kite commences to rise. When the kite is pulled in 'by winding up the string on the reel, it comes back to the tip of the pole thus avoiding damage to the kite and the possibility of the operator being struck by the revolving blades. Q

Referring now to Figure 5, it will be evident that by making this device of largersize, 'it can 'be used as a man-carrying observation kite,

which can be launched from a vessel '50, such as a cruiser or battleship, the altitude of the observer being regulated, if desired, by varying the speed of travel of the vessel. While I have'show'n the towing or tethering means, i. e., rigid element 36 and the flexible element or cord 36', in direct alignment, it will be understood that the tow-line normally flexes somewhat under the pressure of the breeze.

Various modifications may, of course, be made, within the spirit and scope of the following claims, and the invention is therefore not limited in its broad aspects to the exact arrangement shown, nor to the exactproportions and rela- 'tionship of the parts as described, nor to the constructional materials referred to. The preferred embodiment has been described in considerable detail purely by way of example andnot by way of limitation, ii -order to render it easy for anyone following this description to carry the invention into practice.

I claim:

lzAlcaptiv e flight device comprising a body,

a sustaining rotor having autorotatable pivotally mounted blades and a generally upright hub, a tilting fulcrum for the rotor located rearwardly of the hub axis and providing for longitudinaltilt of the rotor, direction and attitude stabilizing surfaces located on the body behind the rotor axis and lateral stabilizing surfaces 10- cated on the body forward of the rotor axis, the center of gravity of the entire device being rearwardly of the rotor tilting fulcrum, a towing member flexibly connected to the body forwardly of the rotor axis, and means for restraining the tilting of the rotor.

2. A captive flight device comprising a body,

a sustaining rotor having autorotatable pivotally mounted blades and a generally upright hub, a tilting fulcrum for the rotor located rearwardly of the hub axis and providing for longitudinal tilt of the rotor, direction and attitude stabilizing surfaces located on the body behind the rotor of the rotor axis and positioned at an angle oi! incidence which is in flight substantially negative with respect to a plane perpendicular to the axis of the rotor, and towing means coupled to said frame forwardly of the rotor axis. I

4. A captive flight device including a frame, a

bladed sustaining rotor constituting the primary means of sustension for the device, the rotor being mounted for movement to difierent angles of incidence in a fore and aft plane, and a non-rotative stabilizing surface located to the rear of the rotor axis and normally positioned in flight at an angle of incidence which is substantially negative with respect to a plane perpendicular to the axis of the rotor throughout the entire range of incidence adjustment of the rotor.

5. A captive flight device including a frame, a bladed sustaining rotor constituting the primary means of sustension for the device, a non-rotative stabilizing surface located to the rear of the rotor axis and positioned at an angle of incidence which is substantially negative with respect to a plane perpendicular to the axis of the rotor, and means responsive to fluctuations in velocity of air flow to increase the angle of incidence of the rotor as a' whole upon decrease in velocity of an flow, and vice versa. 7

6. A captive flight device including a frame, a bladed sustaining rotor constituting the primary means of sustension for the device, a non-rotative stabilizing surface -located substantially rearwardly of the rotor axis and positioned at an angle of incidence which is in flight negative with respect to a plane. perpendicular to the axis of the rotor, a pair of sharply dihedraled stabilizing surfaces laterally spaced toward opposite sides of the axis of the rotor, and a flexible towing apparatus coupled to the device forwardly. of the rotor axis. -.7. A captive flight-device including a frame, a bladed sustaining rotor mounted on the frame with freedom for movement in a'fore and aft plane to different angles of incidence, and mechanism for controlling the angle'of incidence ofthe rotor including a member adapted'to cooperate with the captivating means, for the device.

8. A captive flight device including a body, a bladed sustaining rotor mounted on the body with freedom for tilting movement in a generally fore and aft plane, a member pivotally mounted on the frame having meansadapted to-cooperate with the captivatingmeans, and mechanism interconfor tilting of the rotor said member.

9. A captive flight device incorporating atowmember, a bladed sustaining rotor and stabilizing surfacing, the device being adapted to flight in air flow of diflerentvelocities, and therotor and the said surfacing being relatively positioned and arranged to set up stabilizing moments in the longitudinal vertical plane in opposite senses with respect to the pull of the tow-member, whereby to provide an attitude of substantial equilibrium 'for any given velocity of air flow.

10. A frame for a rotor-kite, comprising a single main longitudinal member adapted to mount tail surfaces at its rear end, a single main upright member secured. to the longitudinal member intermediate its ends and adapted to mount the rotor at ,the top, and a single main transverse member positioned forwardly of the upright member and secured intermediate its ends to the iongitudinal member and adapted to carry lateral stabilizing surfaces at its outer ends. I I

11. In a captive aerial device or the like, a frame or body, a freely revolving rotor mounted on a generally upright axis at the top of said frame, positively dihedraled stabilizing surfaces located at each side of the frame well forwardly of the rotor axis,'and a towing member flexibly coupled to the frame rearwardly of said surfaces.

12.,In a captive aerialdevice or the like, a frame or body, a freely revolving rotor mounted on a generally upright axis at the'top'of said frame, positively dihedraled stabilizing surfaces located at each side of the frame well forwardly of the rotor axis, directional and pitch stabilizing surfaces located on the frame rearwardly of said rotor axis, and atowing member flexibly coupled to the frame rearwardly of said dihedraled sur- A faces.

13. In a captive aerial device. or the like; a frame or body, a freely revolving rotor mounted ona generally upright axis at the top of said frame, said axis being forwardly of the center of gravity, positively dihedraled stabilizing surfaces located at each side of the frame well forwardly of therotor axis and center of gravity, a towmember coupled to the frame forwardly of the center of gravity, and a fulcrum about which the .rotor axis is tiltable in a fore and aft direction,

the range of rotor tilt and the forward location of the lateral stabilizingsurfaces being so related that throughout the range of rotor tilt the liftline of the rotor lies behind the center of pressure of said lateral stabilizing surfaces.

14. In a captive aerialdevice or the like, a frame or' body, a freely revolving rotor mounted on a generally upright axis at the top of said frame, positively dihedraled stabilizing surfaces located at each side of the frame forwardly of the rotor axis, directionaland pitch stabilizing surfaces located on the frame well rearwardly of of the rotor axis, and directional and pitch stabilizing surfaces locatedon the frame rearwardly of said rotor axis, said pitch stabilizing surface being set at negative pitch with relation to the setting of the lateral stabilizing surfaces.

16. In a captive flight device, an autorotatable sustaining rotor including a rotative spindle mounted in a non-rotative sleeve or casing, a

mounting structure for the rotor, a fulcrum for tiltably securing said sleeve in said mounting structure, means for towing or tethering the device, and means for adjusting the rotor fulcrum point to different heights on said mounting structure.

'17. In an aerial device, a frame or body, a rdtatable' sustaining rotor thereabove having a downwardly extending hub or axis located forwardly of the center of gravity of the device, a transverse pivot axis, mounting said hub on the frame for longitudinal tilt of the rotor, and a towing member secured to said frame forwardly of the rotor axis.

l8. In anaerial device, a frame, a rotatable sustaining rotor thereabove having a downwardlyextending hub structure, a transverse pivot axis mounting said hub on the frame for longitudinal tilt of the rotor, a. towing member secured to said frame forwardly of the rotor axis, said tilting axis being positioned rearwardly of the rotor axis, and an interconnection between the towing member and the rotor axis tocontrol tions in position of the former. A I I 19. In an aerial device, aframe, a rotatable sustaining rotor thereabove having a downwardly extending hub structure, a transverse pivot the, rotor axis, and an interconnectionbetween the towing member and the rotor axis to control the tilt of the latter in, acoordance with the variations in position of the former, said interconnection comprising linkage couple to the tow-member and to the rotor axis structure at points respectively below the'point of connection of said member to'the frame and'the point or tilting of the rotor axis.

20. In an aerial device, a frame, a rotatable sustaining rotor thereabove having a downwardly extending hub structure, a transverse pivot axis mounting said hub on the frame for longitudinal tilt of the rotor, a towing member secured to said frame forwardly of the rotor axis, said tilting axis being positioned rearwardly of the rotor axis, an interconnection between the towing member and the rotor axis to control the tilt of the latter in accordance with the variations in position of the former, said interconnection comprising linkage coupled to the tow-memher and to the rotor axis structure at points respectively below the point of connection of said member to the frame and the point of tilting of the rotor axis, and means for adjusting the geometry of said linkage.

21. In an aerial device, a frame, a sustaining rotor thereabove having a downwardly extending hub or axis structure, a transverse fulcrum positioned behind the rotor axis and mounting the same on said frame for longitudinal tilt, a rigid tow-member extending downwardly and forwardly, and a transverse pivot securing its upper end to said frame in a position in front of the tilt of the latter in accordance with the variasaid tiltingv axis being positioned rearwardly of 1 said rotor axis, and motion multiplying means coupling the rotor. axis to the tow-member so that a given angular tilt of the rotor' axis is. accompanied by a greater angular movement of the tow-member.

l 22. In an aerial device, a frame, a sustaining rotor thereabove having a downwardly extending hub or axis structure, a transverse fulcrum positioned behind the rotor axis and mounting the same on said frame for longitudinal tilt, a

rigid tow-member extending downwardly and forwardly, a. transverse pivot securing its upper end to said frame in a position in front of said rotor axis, motion multiplying means coupling the rotor axis to the tow-member sothat a given angular tilt of the rotor axis is accompanied by a greater angular movement of the tow-member, and meansat'the forward lower end of the tow-member for securing the same to a kite string or the like.

' lateral pivotation, means interconnecting the rotor axis and the tow-member, and means limiting the range of pivotation of the tow-member.

25. In a captive flight device, a frame, a towline secured thereto, and an autorotatable sustaining rotor comprising a hub and blades arranged to flap individually with respect to said hub, said blades having means for effecting automatic reduction in pitch of the individual blades under the influence of upward flapping thereof,

and said hub having means providing for automatically controlled variation of the angular position of the hub, within the vertical longitudinal plane, with respect to the frame, whereby to accommodate variations in wind velocity.

26. In a captive flight device, a frame, a' towline secured thereto, an autorotatabie sustaining rotor comprising blades and a hub, said blades having means for effecting automatic variation in pitch of the individual blades, said hub having means providing for automatic variation of the angular position of the hub, within the vertical longitudinal plane, with respect to the frame, whereby to accommodate variations in wind velocity, and means formed as a rigid part of the tow-line pivoted to the frame and having an interconnection with the hub whereby to coordinate the pivotal movement of the latter and of the tow-member.

27. In a captive flight device, an autorotative sustaining rotor, a towing element having flexible connection to the device at a point forwardly of the rotor axis and above the center of gravity of the device, and a negative tail surface rearwardly of the rotor axis and of the center of gravity.

28. In a captive flight device, an autorotative sustaining rotor comprising an axis member and a plurality of rotor blades pivoted thereon, a towing element having pivotal connection to the device about a transverse pivot located forwardly of the rotor axis and below the general point of intersection of the rotor blades and rotor axis,

, a tail surface located rearwardly of the rotor axis, a transverse fulcrumfmounting'the rotor axis for variation of the angle of said axis within the vertical longitudinal plane, and means coupling together the said towing element and rotor axis member so constructed that when the rotor is at high angles of attack the pull of said element is on a line passing rearwardly of said point of intersection and when the rotor is at low angles of attack the pull of said element is on a line passing forwardly of said point.

29. In a captive flight device, an autorotative sustaining rotor, a towing connection to the device forwardlyof the rotor, a negative tail surface rearwardly of the rotor, and means for bodily shifting the position of the rotor axis.

30. A captive flight device comprising a body having stabilizing surfacing, a sustaining rotor having autorotatable pivotally mounted blades and a generally upright hub, means for shifting the lift-line of the rotor relative to the center of gravity of the device, and a towing member for the device coupled to the last named means to control the same.

31. In a captive flight device, a body, an autorotative sustaining rotor thereabove having an axis positioned forwardly of the center of gravity of the body, a towing connection to the device forwardly of the rotor axis, and means for bodily shifting the position of the rotor axis in the longitudinal vertical plane. 3 I

I CARL B. CHUPP. 

